Horizontal wavy lines in under print on back. Back printed drfa to left of front.
Variations within specific set:
Under print wavy line direction on back vertical or horizontal
Reverse printed same way up as front or upside down.
Misprint colors 10h: red brown, 20h: Brown, 50h Black
Variations in larger set:
Under print and print colors
Overprints
Stamps
With or Without under print
More than 60 versions.